Nonlinear Weighted-Least-Squares Estimation Approach for Gas-Turbine Diagnostic Applications

the summation of weighted square deviations between estimated and actual values of gas-turbine performance measurements. The measurement uncertainties associated with gas-path measurements are taken into account by using a weighting matrix. The concepts of fault cases and gas-path-analysis index are introduced. These provide a newdiagnosticapproach,enablingfaultisolationandenhancingtheconfidenceofdiagnosticresults.Thisdiagnostic approach allows the typically nonlinear gas-turbine thermodynamic-performance models to be directly used in condition monitoring while taking into account performance nonlinearities. An iterative calculation process is introducedtoobtainaconvergedestimationofenginedegradation.Thenonlinearweighted-least-squaresdiagnostic approachhasbeenappliedtoamodelindustrialgas-turbineenginetotestitseffectiveness.Thenumericaltestsofthe new diagnostic approach show that with appropriate selection of engine gas-path measurements, the method can be used effectively and successfully to predict gas-turbine performance degradation.